Antiicing screen



May 9, 1950 c. s. JEwETT ETAL 2,507,018

ANTIICING SCREEN Filed May 8, 1948 2 Sheets-Sheet 1 ATTO RN EY T. 8 2 n n l L5-Lr o., .n 5mn-m v e Y 0 m ITM. w 5., y N AAA m 2 t EIL o e LRN T NRE-L T. s Anw? A 2 was Y B L A n m .A n w ...A E G w m J H l2 m M 3 B A a o 6 c 4 l, M

4 w.. l..2 w 2 ,A 0 l 9 8 1|. y 7 a 9 M Y w a .n M F Patented May 9, 1950 AN TIICIN G SCREEN Charles S. Jewett, Ramsey, anack Lake, and Euge Ridge, N. J., assignors t Corporation, a corporat Robert A. Loos, Packne A. Mehnert, Park o Wright Aeronautical ion of New York Application May 8, 1948, Seria-1 No. 25,956

(Cl. 21S- 19) 8 Claims.

This invention relates to screens for fluid ducts and is particularly directed t a screen for the air intake duct of an engine for preventing the entrance of foreign objects into said duct, said screen including means for heating its parts to prevent the formation of ice thereon. The in vention has been designed in connection with the annular air entrance duct of a gas turbine power plant for aircraft. As will appear, however, the invention is of general application.

It is conventional practice to provide a screen for the air intake duct of an engine to prevent the entrance of foreign objects into said duct. In the case of aircraft engines, the condition of the engine intake air frequently is such that ice forms on any structure in said duct, such as said` screen, over which said intake air flows. The presence of ice in the engine intake duct reduces or throttles the engine air iiow therethrough thereby reducing the power output of the engine. An object of this invention comprises the provision of a novel and improved screen construction including means for heating all the elements of the screen to prevent the formation of ice thereon. In addition the invention has the further object of providing a novel screen construction offering only a small resistance to air flow therethrough.

Other objects of the invention will become apparent upon reading the annexed detailed description in connection with the drawing, in which:

Figure 1 is an end View of an annular air intake duct having a screenconstruction embodying the invention;

Figures 2 and 3 are sectional views taken along lines 2 2 and 3-3 of Figure 1;

Figure 4 is a sectional View taken along line 4-4 of Figure 3;

Figure 5 is an exploded perspective view of a portion of one oi the struts illustrated in Figure 4; and

Figure 6 is a schematic wiring diagram of the electric wires incorporated in the screen of the present invention.

Referring to thev drawing, reference numeral I8 indicates the forward end of a gas turbine aircraft engine which comprises an air intake passage I2 having an annular outer wall I4 and an annular inner wall IB. The inner wall I6 is supported from the outer Wall I4 by a plurality of circumferentially spaced and radially disposed' struts I8 and a strut I8. The strut I8' comprises the upper strut in Figure 1 and, except as here-v inafter described, is identical' with the struts I8;

The struts I8 and I8 are inclined to the axis of the annular passage I2 such that their radially outer ends are disposed downstream of their radially inner ends.

Each strut I8 has a composite construction which comprises a trailing edge member 20, a leading edge member 22, and a pair of comblike intermediate members 24 and 26. The intermediate comb-like members 24 and 25 are made of suitable electric insulating material while the leading edge member 22 and the trailing edge member are made of suitable metallic material. The intermediate comb-like member 24 has a pair of longitudinal grooves 28 along its opposite sides within which inwardly turned tongues or anges of the trailing edge mem ber 28 are arranged to be snugly and slidingly received. Each trailing edge member 20 also has a strengthening web 32. The radially spaced ends of each trailing edge member 2G are secured to the walls of the annular passage I2, for example by welds 34, either before or after said member and its associated comb-like member 24 are assembled together. If a trailing edge me1n ber 2!! is first secured to the walls of the duct I2, then its intermediate member 24 may be assembled therewith by sliding said intermediate meinber radially inwardly along said trailing edge member with the iianges 30 received within the grooves 28. Each comb-like member 24 has a plurality of teeth 36 extending therefrom. After each trailing edge member 20 and its comb-like member 24 have been secured across the passage I2, a suitable electric resistance wire 38 is spira1- ly wound across the passage, said wire being sup ported at the bottoms of the spaces between the teeth 3B of the members 24.

After the spiral resistance wire 38 is disposed in position on the comb-like member 24, the comblike members 26 are assembled on their respective comb-like members 24. Thus, each comblike member 26 has teeth 40 which are adapted to be snugly received within the inter-tooth spaces between the teeth 36 of the comb-like member 24. The teeth 40 are shorter than the teeth 36 thereby leaving passages across the ends of said short teeth, and the bottoms of their respective inter-tooth spaces, the wire 38 extending through said passages. The arrangement is such that the teeth 40 snugly hold the wire 38 against the bottoms of the inter-tooth spaces in the member 24.

When a pair of comb-like members 24 and 2S are disposed in assembled relation, notches 42 in both sides of the teeth 36 of the member 24 are atomic ends of the leading edge members 22 are suitably secured to the walls of the passage fI2, for Iexample by welds 48. A suitable 'plate 49 lis Welded to and across the inner end oi" each lleadi-rig gedge member 22 so as to lock the members 26, 252, 2f4

and 26 of each strut against relative longitudinalmovement.

The leading edge of each comb-like fmember 26 is provided with a longitudinal groove 50 along which a suitable .insulated-electric resistance wire 52 is adapted to ube disposed. Obviously the wires 52 Amay be disposed in .position feither .prior to, during, or after their respective :leading @edge members 22 are assembled inposition.

The structure of the r'strut I8' is substantially the same as -thatof the struts iI'-so-thatthe .parts of the strut I8 Ahave been-designated Yby similar' but primed 'reference numerals fas the corresponding parts qof the struts t8. -In the strut I8', :theteethl ande-S', of the comb-like mem-- bers '24' and 126'., respectively, 'are :inclined Jto, the long dimension'of thezstrut Vto .facilitate the lspiral configurationof :the screen Wire'll, iis-illustrated 1x1-Figure i. YExcept for the inclinedfdisposition of the teeth 36'l and thatloithemating teethelill., the-structureofthestrut I6 is identical to that-of the struts "I8,

The outer wall =I'4 of the annularfduct 42 lhas a hollowconstruction and-a Aterminal ,box 54 is disposed therein over the'strut I8. -Asuitable sourceof -electric 'energy Vis connected to a v`pair of terminals-56 -and-Sf'in the lbox 54 byv-meansof wires'ieand 62. VAsseen in-Figures 1 and-6, one

terminal-58; is connectedtolthe--outerend of the spiral Vresistance wire 38 .and the other fterminal 56 isfconnected to the `outer :end of 'the leading edge wire-52-of'the1strut I6'. The inner-end-.of said-siral Wire-38 is connected lto one-endof-a jumper conductor 6d, the -other `'end .of which connects 1with theinnerend of the yleading-edge wire W52 -of the adjacent clockwise-spaced strut I8, as viewed in Figure l. 'Ehe'outer endofsaid last mentioned'leadingiedge wirei52connects with one end .of a jumper conductor-"66, theotherend of which connects Iwith the wouter yend of 4.the next clockwise-spaced leading edge vwire 52. In

this :way the Ajumpers 6i1and66serially connect the leadingedge-wiresff'si with the spiral wirefi.

The-.struts trand .I' together withthe Vspiral Wire 38 :provide screen construction disposed acrosstheintalre'duct I2 toprevent the .entrance of foreignobjects therein. illiththis .screen .conf struction, when the conditions of theairentering the intakeduct I2.arezsuchthatiicing .isgor may occurl inside said duct, lthenA electric .powerL is supplied toithe terminals.56 andqwthrough Athe wires 66 4and l6,2. The vresulting current flow through the leadingedge wires 52 heats up=the Aleading edges ofthe struts i8 andif ofthe screen to pre-` venttheliorination` of ice Von saidstruts. In-addi-f tion the flow ci' current through the spiral mire 38 heatsup-this portion .of .the screen to V.prevent the .formation of =ice1thereon- The amount-cf electric energy-requiredto befsupplied tothaterf minals 56 and 58 in order to prevent the formation of ice on the screen obviously depends on the quantity of air owing through the duct I2 as Well as on the temperature of said air.

If desired, it is possible to pass enough current through the screen wires to heat up the air ow- .ing through the -screen in order -toalso prevent ice .formation downstream .of the screen.

The composite structure of each strut with its comb-like members and leading and trailing edge members, provides a construction whereby the Wire screen can readily be disposed across the l:duct I2 and supported from the struts. When the various fmembers making up each strut are sekcuredtogether,said struts all have a streamlined fcross-section'with -o'nly the inter-strut lengths of the spiral Wire .38 projecting therefrom. The spiral wire`38 may also be provided with a streamlined vcross-section. The struts I8 and I8 have the further function of supporting the inner vwall .I6 -ofthe passage EI2 fromvthe outer wall I4 o flsaid passage.

Beca-use -oi -the inclination-.of `the .struts I8 and 18', to itheaxisof the passage I2, there isonly-one turn of the spiral wire 3,6 in any plane transverseto the ,axis of :the intake .passagel2. That isreach .tur-noi `therspiral wire 38 is disposed in a plane which .is axially spaced from the plane of any-otherAturn-of said Wire. With this :staggered disposition yofthe :tur-ns -of .the vspiral Wire 38, the screen formed thereby oiers -a much smaller resistance to air vfiow.therethrough than'would be the icase if `all the wire turns were :disposed in the same .-plane.

While we have described your invention in detail-in its v,present preferred embodiment, it Will be-obvious yto fthoseskilled .in Ythe .ar-t, after understandingpur invention, that Ivarious changes and modifications-may be made thereinwithout departing from .the .spirit Vor scope thereof. We aim in the .appended claims to cover Aall such modifications.

We claimfasoin'finvention:

1. vA screen `for` anrannular uid ductrcomprisinga plurality of .strutszextending between .the innerandouter walls ofsaid .duct-for supporting said Ainner Wall, l.said .struts .being vdisposed so that the radially inner and outerends .of-each strut .are axially .spaced @relative -to the -axis of said iduct; 1and .a plurality .of .radially spaced .lengthslof electric lwire extending between yand carried by each pair of adjacent struts; .and kmeans Vfor connecting said Lwires vto .a .source -of electric-current.

2. A screen'for an annular fluid duct .comprising a plurality .of :struts .extending .between .the inner and outer Wallslof.fsaidfductfor A support- .ing-saidy inner iwall, `said .struts .being disposed so that the radially inner and outergendsvof each strut are axially -spaced :relative `to :the y axis .of said duct; v4an .elec-tric .wirefcarried -by and =dis posed along the leading edge of each of .said struts; andfarplurality of-iradially spaced lengths of-electric V.wire :extending v.between and carried by each pair of adjacent struts; andimeans.fory connecting` saidvwires .toa 'source of electric .current'.

.3. A screen forv an .annular fluid ductcomprising aplurality-of.radially.disposedfstrutsz extend-- ing fvbe-tweenthe v.inner and tou-ter walls of lsaid duct Eforsupporting said inner wall .an felectric wire carried r'by and: disposed. a-longsthe leading edge A.of yeach `'of-.said,struts; rand a fpluralityof radiallyespaced-.lengths offelectric wire extending between land carried. xivy each, pair of :adjacent struts; and means for connecting said wires to a source of electric current.

4. A screen as recited in claim 3 in which each of the wire lengths extending between a pair of adjacent struts is axially spaced, relative to the duct axis, from each of the other wire lengths between said pair of struts.

5. A screen as recited in claim 3 in which each of said struts includes a pair of comb-like members, each of said comb-like members having its teeth received within the inter-tooth spaces of its paired comb-like member, the teeth of one of said comb-like members being shorter than the teeth of the other of said members thereby forming passages between the ends of said short teeth and the bottoms of the inter-tooth spaces in which said short teeth are received, said lengths of wire being supported by said struts in said passages.

6. A screen as recited in claim 5 in which each of said comb-like members is made of electric insulating material.

7. A screen as recited in claim 3 in which each of said struts has a composite construction including a trailing edge member, a leading edge member and a pair of intermediate comb-like members secured to said first mentioned members, each of said comb-like members having its teeth received within the inter-tooth spaces of its paired comb-like member and the teeth of one of said comb-like members being shorter than the teeth of the other of said members thereby forming passages between the ends of said short teeth and the bottoms of the intertooth spaces in which said short teeth are received, said lengths of wire being supported by said struts in said passages.

8. A screen as recited in claim 7 in which each of said leading edge strut members has a flange received within grooves in each of its associated intermediate comb-like members for securing said members together.

CHARLES S. JEWE'IT. ROBERT A. LOOS. EUGENE A. MEHNERT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,102,249 Denhard July 7, 1914 1,161,667 Hays Nov. 23, 1915 1,905,770 Walker et al. Apr. 25, 1933 2,260,233 Ripley Oct. 21, 1941 2,409,954 Pearson Oct. 22, 1946 2,435,990 Weiler Feb. 17. 1948 

